Research Highlight

Plasmid protein points to ancient DNA-protein interaction

doi:10.1038/nindia.2012.33 Published online 14 March 2012

Looking at the evolutionary connection of a plasmid protein, researchers have unraveled the possibility that some proteins and their binding sites might represent ancient DNA-protein interaction modules.

The researchers were working on mycobacterial plasmid (pAL5000), which represents a family of plasmids found mostly in the Actinobacteria. This plasmid replicates using two plasmid-encoded proteins — RepA and RepB.

While there is some evidence that RepA is a replicase family protien, not much was known about the the evolutionary connection of RepB.

To obtain insight into the structure-function and evolutionary connections of RepB, the researchers used homology modeling, phylogenetic, and mutational analysis methods. The results showed that although they are synthesized from the same operon, the phylogenetic affinities of RepA and RepB differ.

The operon may have evolved through random breaking and joining events, the researchers say.


  1. Basu, A. et al. Evolutionary Link between the Mycobacterial Plasmid pAL5000 Replication Protein RepB and the Extracytoplasmic Function Family of σ Factors. J. Bacteriol. 194, 1331-1341 (2012) | Article | PubMed |